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By Fred D. DeVaney

DURING the past few years a radically new process for the magnetic roasting of iron ores has been investigated and developed by Pickands Mather & Co. and the Erie Mining Co. in the Erie laboratory at Hibbing, Minn. This process, originally devised by Dr. P. H. Royster of Washington, D. C., involves the use of a roasting technique quite different from older methods. It has now been demonstrated that iron-bearing materials can be roasted as effectively as by any previously known method, and at a much lower cost. The increasing shortage of highgrade iron ores in this country has accelerated the search for new methods that would permit low grade materials to be utilized. The concept of magnetically roasting low grade nonmagnetic ores such as the oxidized taconites and then separating such material magnetically has always had considerable appeal. The magnetic concentration idea is attractive because of the sharpness of the separations and cheapness of the method. Heretofore, however, the equipment and the processes available for the magnetizing-roasting -step have left much to be desired. The customary equipment available for reduction roasting has been: 1-multiple hearth furnaces, 2-rotary kilns, and 3-shaft type kilns. In addition, it is understood that some work has been done in magnetically roasting fine ores by a process using the FluoSolids principle, but little information on this process is available. The multiple hearth kiln has been used the most but first costs and operating costs have been high because of low capacity, high maintenance, and poor gas utilization. Magnetic roasting can be done in a rotary kiln, but the radiation losses are high and the conversion to magnetite is usually unsatisfactory because of poor contact between the gases and the solids. Of the shaft-type furnaces, probably the most efficient yet developed is that designed by E. W. Davis of the Minnesota Mines Experiment Station. This furnace was operated at Cooley, Minn., during 1934-1937 but was abandoned in 1937 because the operation was uneconomic. Heretofore the basic concept behind most magnetic roasting processes has been the idea of heating iron ore to a temperature of 800° to 1100 °F in a strong reducing atmosphere, preferably either carbon monoxide or hydrogen. Temperatures under 800°F were undesirable since excessive roasting time was required. Temperatures over 1100°F were avoided because of the danger of converting part of the iron to ferrous oxide which is nonmagnetic. In the new roasting process, the operation is carried on in a shaft furnace using a controlled atmosphere containing a low percentage of reducing gas. The temperature in the roasting zone is considerably higher than with the usual reducing gas and this speeds up the reduction time. Portions of the spent furnace gases are cooled and recirculated and this together with the good contact between ore and gas makes for high reducing gas utilization. High heat economy is secured by recuperating heat from the roasted ore by passing the cold reducing gases countercurrent to flow of ore. The heat transfer principle is similar to that employed in a pebble stove and to that used in the Erie Mining Co. furnace at Aurora, Minn., for pelletizing fine magnetite concentrates derived from taconite. The theory of controlled atmosphere during the roasting operation can best be appreciated by inspecting the equilibrium diagram of the Fe-C-O system shown in Fig. 1. An inspection of this diagram shows that in certain areas magnetite, Fe3O4, is the only stable form of iron. A further inspection of this table shows that if the proper ratio is maintained between carbon dioxide to carbon monoxide, such a gas will be reducing with respect to hematite, Fe2O3, and will be oxidizing with respect to both ferrous oxide, FeO, and iron, Fe. It should be kept in mind that the formation of ferrous oxide in a roasting operation is harmful, since this oxide is nonmagnetic; if it forms in any quantity, it will cause substantial loss of iron in the ensuing magnetic separation step. If a ratio of approximately three parts carbon dioxide to one of carbon monoxide is maintained, the resulting operation can be carried on at a relatively high temperature without fear of over-reduction. Specifically, most of the tests in the Erie furnace have been made at a temperature of 1500° to 1600°F, with an entrant gas containing approximately 5 pct carbon monoxide and 15 pct carbon dioxide, with the remainder largely nitrogen. It should be remembered that the ratios of carbon monoxide to carbon dioxide shown in Fig. 1 hold even though the bulk of the gas is an inert gas such as nitrogen. It may surprise many to learn that a gas containing as low as 3 pct carbon monoxide, and 12 pct carbon dioxide with the remainder nitrogen is an extremely effective reducing gas in the 1000° to 1600°F temperature range. The reducing gas is not limited to carbon monoxide, and mixtures of hydrogen and carbon monoxide may be used effectively, provided that a similar ratio is maintained between the reducing gases and carbon dioxide and water vapor. For a more detailed explanation of the theory involved, the reader is referred to U. S. patents 2,528,552 and 2,528,553. From a safety standpoint, the weak reducing gas used in the furnace offers an advantage. Its composition is such that it is well below the limits of explosion should air enter a hot furnace. This condition is not true with the usual reducing furnace, in which a gas rich in carbon monoxide or hydrogen is used. The general furnace design and method of operation may best be understood by an inspection of

Jan 1, 1952

By Robert W. Shearman

An historical record of the history of iron-and steelmaking in the United States has long seemed a desirable project to many in The metallurgical Society of AIME. Over a period of five years, experts in their fields have been asked to put down on paper their knowledge. The series of historical articles has been published in JOURNAL OF METALS, beginning with A. B. Wilder's article in 1956, marking the first one hundred years of Bessemer Steelmaking. The Electric Furnace Committee honored the first half-century of the use of the electric arc furnace in America during their 1956 Conference, and S. B. Casey, Jr., wrote an appropriate article for JOURNAL OF METALS. The historical series was well underway. Articles soon followed on the history of the blast furnace, on the open hearth furnace, and on ferro-alloy manufacture. The final need was an authoritative article on coke ovens. The publication of the five-part article by C. S. Finney and John Mitchell this summer has concluded our series (but not the march of progress). We now present, between two covers, a comprehensive historical review, the work of 13 authors. We are hopeful that this book will receive a welcome among ironmakers and steelmakers. and that it will be a valuable reference for home or office library. We hope also that students will find the material helpful in their studies of this most important of American industries. Perhaps also, the historian of Americana will learn something new in searching through these pages. We are indebted to our authors who have spent much time on historical research, and to their companies who have supported their endeavors. We acknowledge the support of the National Open Hearth Steel Committee and of the Blast Furnace. Coke Oven, and Raw Materials Committee in jointly assuming the financial risks in publishing this book.

Jan 1, 1961

By J. E. Flinn, J. M. Welch, R. L. Miller

Introduction Two samples of an iron-enriched basalt (IEB)-a silicate-based fused-cast ceramic waste form-containing components that simulate Three Mile Island Unit 2 core debris were tested for uranium recovery (Miller et al., 1984). This material is highly refractory towards leaching by ground water. The uranium content is high (15.1%) and the U-235 content (2.57%, only

Jan 1, 1986

PRESIDENT BENJAMIN B. THAYER,2 NEW YORK, N.. Y. PAST PRESIDENTS JAMES F. KEMP,1 NEW YORK, N. Y. CHARLES F. RAND,2 .NEW YORK, N. Y. FIRST VICE-PRESIDENT SIDNEY J. JENNINGS,1 NEW YORK, N. Y. TREASURER GEORGE C. STONE,1 NEW YORK,. N. Y. SECRETARY EMERITUS ROSSITER W. RAYMOND, NEW YORK, N.Y. SECRETARY BRADLEY STOUGHTON NEW YORK, N. Y.

Jan 9, 1914

By Klaus Schwerdtfeger, Leo Zwell

The equilibrium between Ir-Fe or Rh-Fe alloys, iron oxide (wüstite or magnetite), and CO2-CO atmospheres has been determined at 1200°C. The data are used to derive the activities in these binary solid solutions. Both systems show negative deviations from Raoult's law. The lattice parameters are given for the investigated Ir-Fe and Rh-Fe alloys. IRIDIUM and iron form a continuous series of fcc solid solutions at elevated temperatures.' Rhodium-rich Rh- Fe alloys have fcc structure.' In the medium concentration range an ordered bcc phase is stable at temperatures up to about 1300°C. Phase relations in iron-rich alloys are not well-known. No thermody-namic data are available for these alloys. EXPERIMENTAL METHOD The experimental method used was to measure the equilibria between a gas phase of known CO2/C0 ratio, the alloy, and iron oxide (wüstite or magnetite). In one series of experiments the alloys of known composition were heated in CO 2-CO gas mixtures. After treatment (usually 1 day) the sample was quenched to room temperature and its surface examined visually to determine whether an oxide tarnish had formed. The procedure was repeated at slightly higher CO 2/CO ratios until the CO 2/CO ratio of incipient oxidation was found. Subsequently, the CO 2/C0 ratio was lowered again in small increments until the tarnish was reduced. In other experiments mixtures of alloy and iron oxide powders were pressed into pellets and equilibrated with the CO2-CO gas phase. In order to ensure that equilibrium was attained, two specimens with different starting iron content were heated side by side; in most cases, equilibrium was approached in one pellet by reduction of iron oxide and in the other pellet by oxidation of metallic iron. The sample was quenched to room temperature, and the composition of the equilibrated alloy was determined by X-ray measurements of lattice parameters and comparison of these values with calibration curves obtained from alloys of known composition. The oxides present in the specimens were identified by comparison of their diffraction patterns with those in the ASTM Card File. It may be expected from the noble character of iridium and rhodium that no appreciable amount of iridium or rhodium is dissolved in wiistite and magnetite under the present experimental conditions. The activity of iron in the alloy is then equal to that established in the iron oxide by the COrCO atmosphere. The activities of iron in wüstite and magnetite, as a function of oxygen pressure, were taken from the work of Darken and Gurry,

Jan 1, 1969

By Y. Ueda, F. Noguchi, T. Yanagase

The rate of CaO dissolution into slag melts is of great importance in the field of pyrometallurgy. In this study the mechanism of CaO dissolution has been investigated by observing the melt heated on Pt-filament directly through microscope together with a help of X-ray micro analyser to find out a distribution of each element around CaO crystal. The direct observation reveals that the CaO dissolution tends to proceed by the action of molten slag entering between CaO crystal and newly formed 2Ca0. Si02 layer through cracks. The effect of slag composition on the formation of 2CaO- SiO2 layer will be shown as well as the effect of halogenides addition on the destruction of this compound layer.

Jan 1, 1976

By Ralph W. Smith

Development of the lime industry in Ste. Genevieve County began in a crude way in 1840. According to information furnished by the Missouri Bureau of Geology, in the early days small vertical kilns built of stone were used, and wood was the fuel. Modern development began in 1904 when one company introduced steel shells lined with firebrick. Within a few years two more companies erected similar plants, and in 1925 a fourth company began operations. Thus there arc today four lime companies at Ste. Genevieve, all operating at high capacity and with a gradually increasing production. Geology The limestone of Ste. Genevieve County, which has the chemical composition and purity required for lime burning, is the upper 80 or 90 ft, of Spergen formation. The Missouri Bureau of Geology, in its geological map of Ste. Genevieve County, gives the Spergen formation a total thickness of 160 ft., but only the upper portion is pure enough for lime burning, with an average raw-stone analysis of 98.7 per cent CaCo3; 0.35 SiO2; 0.3 R2O3; 0.35 MgCO3; 0.3 SO3. The Spergen, one member of the Meramac group, Iowa series, of the Mississippian system, underlies an area approximately 12 miles long north and south, by 5 miles wide east and west (Fig. 1) in Ste. Genevieve County. The entire eastern two-thirds of Ste. Genevieve County is sedimentary, the formations dipping gently toward the east on an average grade of about 4 per cent, or 2 1/2°. Thus the outcrops of the various sedimentaries run approximately north and south. A line running west from Ste. Genevievc crosses the outcrops of the sedimentaries, ranging from the top of the Mississippian to the Ozarkian geological system in a space of 12 miles. Thus with the gentle dip of 2 1/2° the 160-ft. thickness of the Spergen formation stretches out in its outcrop so that it is approximately one mile wide. The early quarry and lime developments at Ste. Genevieve mere in this easily obtained surface rock of the Spergen outcrop.

Jan 1, 1938

By Ralph W. Smith

Development of the lime industry in Ste. Genevieve County began in a crude way in 1840. According to information furnished by the Missouri Bureau of Geology, in the early days small vertical kilns built of stone were used, and wood was the fuel. Modern development began in 1904 when one company introduced steel shells lined with firebrick. Within a few years two more companies erected similar plants, and in 1925 a fourth company began operations. Thus there arc today four lime companies at Ste. Genevieve, all operating at high capacity and with a gradually increasing production. Geology The limestone of Ste. Genevieve County, which has the chemical composition and purity required for lime burning, is the upper 80 or 90 ft, of Spergen formation. The Missouri Bureau of Geology, in its geological map of Ste. Genevieve County, gives the Spergen formation a total thickness of 160 ft., but only the upper portion is pure enough for lime burning, with an average raw-stone analysis of 98.7 per cent CaCo3; 0.35 SiO2; 0.3 R2O3; 0.35 MgCO3; 0.3 SO3. The Spergen, one member of the Meramac group, Iowa series, of the Mississippian system, underlies an area approximately 12 miles long north and south, by 5 miles wide east and west (Fig. 1) in Ste. Genevieve County. The entire eastern two-thirds of Ste. Genevieve County is sedimentary, the formations dipping gently toward the east on an average grade of about 4 per cent, or 2 1/2°. Thus the outcrops of the various sedimentaries run approximately north and south. A line running west from Ste. Genevievc crosses the outcrops of the sedimentaries, ranging from the top of the Mississippian to the Ozarkian geological system in a space of 12 miles. Thus with the gentle dip of 2 1/2° the 160-ft. thickness of the Spergen formation stretches out in its outcrop so that it is approximately one mile wide. The early quarry and lime developments at Ste. Genevieve mere in this easily obtained surface rock of the Spergen outcrop.

Jan 1, 1938

By A. H. Daane, J. J. Hanak, F. H. Spedding

IN the study of the rare earths at the authors' laboratory, methods have been devised for preparing pure rare earths and many of their properties'- have been determined. Very little information is found in the literature on the properties of europium metal, which is the scarcest of the naturally occurring rare earths. Since we have recently prepared europium in appreciable quantities, we are in a position to describe the method of preparation and some of the properties of this metal. Metallic europium was first prepared by Klemm and Bommera who heated a mixture of potassium and EuC1, in vacuo, and obtained a mixture of europium metal and KC1. Trombe4 electrolyzed a molten salt bath containing NaC1, KC1 and EuC1, and collected the europium in a molten cadmium electrode as a cadmium alloy. The cadmium was subsequently removed by distillation but the properties of the residue indicate that pure europium was not obtained. McCoy attempted to prepare europium by distilling mercury from europium amalgam, but the stability of the Eu-Hg intermetallic compounds prevented a complete separation of the two elements. The preparation of very pure europium was suggested by previous work in this laboratory1,4 in which ytterbium and samarium were prepared by heating the respective sesquioxides with lanthanum metal turnings to 1450°C in vacuo and distilling ytterbium and samarium from the mixtures. Subsequently, small test experiments showed that europium also could be prepared by this method. A more detailed version of this method was used in the work described in this paper. Klemm and Bommer3 found by X-ray analysis that the metal had a body-centered cubic (bcc) structure with a lattice constant a, = 4.582 ± 0.00A (converted from kX units), with a bulk density of 5.30 g per cu cm. They found europium to be weakly ferromagnetic. Spedding, et al,7 found a,, to be 4.606 ± 0.001A. Barrett' showed that the bcc structure persists throughout the temperature range 5 to 3000K with a, at 5, 78, and 300°K being 4.551 ± 0.003, 4.551 ± 0.004 and 4.577 ± 0.001A, respectively. Trombe1 described europium as being iron gray, malleable, about as hard as neodymium and not attacked by cold water. He estimated the melting point to be between 1100 and 1200°C. Previous work in this laboratory indicated that the pure metal corrodes rapidly in air and reacts with cold

Jan 1, 1959

By G. A. Parks, C. Kovacs

The xanthate flotation of chrysocolla can be improved by preheating the ore to 500° to 600°C. Addition of water vapor reduces the preheating temperature required. The temperature range of flotation improvement correlates well with the range over which dehydroxylation occurs. This observation is consistent with changes in the structure and properties of the mineral as detected by measurement of solubility, D.T.A., T.G.A., X-ray diffraction, and infrared absorption and with recently proposed explanations of chrysocolla flotation. A brief experiment by one of the authors several years ago showed that exposure of chrysocolla to high temperature water vapor resulted in increased recovery by subsequent xanthate flotation. Recently renewed interest in flotation and thermal properties of chrysocolla1-5 prompted further study of this effect and more detailed reporting.6 This paper explores the response of pure chrysocolla recovery in Hallimond tube flotation tests to the time and temperature of exposure and to changes in the water vapor pressure. Brief attention is paid to the effects of such treatment on accessory minerals. A single experiment with flotation of chrysocolla from an ore is reported. MATERIALS Chysocolla from Inspiration, Gila County, Ariz. was crushed in a porcelain mortar, cleaned of visible and magnetic impurities, and screened to obtain -48 +65 mesh (Tyler) material for flotation test work. The clean material contained 28.5% Cu and was identified as chrysocolla by comparison of X-ray diffraction, D.T.A., and infrared absorption data with that reported for similar materials by others.4,5,7 Samples of malachite and chalcopyrite, prepared in a similar way, were also identified by X-ray diffraction. The sources of these materials are unknown. A sample of chysocolla-bearing oxidized copper ore from Pima, Ariz. was crushed and dry ground for thermal activation and subsequent flotation. PROCEDURES Activation: The apparatus used for exposure of materials to high temperature water vapor is illustrated in Fig. 1. The furnace temperature was controlled to ±5°C Water vapor pressure was controlled by pre-saturating a nitrogen carrier stream with water in an adjustable thermostatted saturator (multiple bubbler). A water manometer and capillary orifice flow meter were used to measure nitrogen flow rates for activation and for subsequent Hallimond tube tests. Gas flow rate and temperature were adjusted prior to introduction of samples. Exposure time was measured from the moment of introduction of the sample to the furnace, hence includes an initial drop below the control temperature. After heating, the samples were removed from the furnace and stored at room temperature in air. Representative samples of activated materials were examined by X-ray diffraction and infrared absorption.

Jan 1, 1967

PRESIDENT BENJAMIN B. THAYER,2 NEW YORK, N. Y. PAST PRESIDENTS JAMES F. KEMP,1 NEW YORK, N. Y. CHARLES F. RAND,2 NEW YORK, N. Y. FIRST VICE-PRESIDENT SIDNEY J. JENNINGS,1 NEW YORK, N. Y. TREASURER GEORGE C. STONE,1 .NEW YORK, N. Y. SECRETARY EMERITUS ROSSITER W. RAYMOND, NEW YORK, N. Y. SECRETARY. BRADLEY STOUGHTON NEW YORK, N. Y.

Jan 7, 1914

By Kenneth K. Humphreys, F. R. Zachar, A. G. Gilbert

INTRODUCTION by F. R. ZACHAR and A. G. GILBERT Coal producers are not only faced with the problems of mining coal, but must also decide to what extent they can invest capital and what operating and maintenance expense they can afford, after mining, to market their product in sufficient volume and at a reasonable profit. Regardless of whether the operator is contemplating a new operation or merely considering expanding present facilities, market requirements, ability to make a product meeting requirements, probable costs and possible future changes in raw coal or finished product must be considered. In addition, such items as flow sheet, structural designs, storage facilities, etc, must be examined individually and collectively. In estimating preparation costs to meet predetermined market specifications, the operator must calculate the economics of present preparation practices to anticipate the increase to total production which results when the quality of the finished product is increased. The consumers of coal are continually seeking to obtain the best and most adaptable product for their money. Regardless of whether coal is used for coking, industrial requirements, electric power generation, domestic fuel or for other purposes, it will be scrutinized from such standpoints as delivered cost, suitability for utilization in certain equipment, ease of ash disposal, adaptability to material handling system plans and its potential for generating dust problems. Utilities, due to large capacity volume requirements, are generally in a position to select coal that will result in the lowest over-all cost per million Btu. Freight costs, paid by the utility, are important and are given utmost consideration when a coal is under consideration. Steel companies, whether producing or purchasing coking coal, are continually seeking coal that will result in lowering the cost of pig iron production. Since it is usually necessary to clean to lower specific gravities, say 1.40, to turn out a product meeting metallurgical requirements, it follows that a high ash "middling" product is created. These low quality middlings do not command a good price. Therefore, unless the metallurgical coal can command sufficient realization to carry or subsidize the middlings, the operator may be ahead economically to prepare steam coal at a higher specific gravity. While the "unit-train" rate reductions have been helpful to the economy of the coal industry, the establishment of these rates has made mandatory the installation of storage and rapid car loading facilities at mines and plants shipping utility coal (see Chapter 15). A study of the economics

Jan 1, 1968

By E. Luttgen

The substance referred to in the title is the artificially prepared basic carbonate of magnesia, a compound of the carbonate with the hydroxide. It is the "block-magnesia " of commerce, the magnesia alba of the pharmacist. Its composition, though somewhat indefinite, may usually be expressed by the formula : 4MgCO3,Mg(OH)2, 5H2O; it is found to vary slightly with the details of the method of preparation. This substance has been employed recently with much reported success, as a non-conductor of heat. It is moulded to form coverings suitable for steam-pipes and their fittings and sectional jackets for boilers and cylinders; it is furnished also in forms suitable for lining refrigerators, walls and roofs of buildings, fire-proof safes, etc. It was with a view of ascertaining the efficiency of this material as a non-conductor, or, rather, its relative efficiency among the various non-conducting materials in use, that the writer made the experiments about to be described. A block of magnesium carbonate or magnesia alba exhibits some interesting physical qualities. It is a smooth, white, close-grained solid, in outward appearance resembling a block of Paris plaster. It possesses the lightness of cork, the porosity of sponge, and withal a degree of firmness and strength that, in view of its levity, is quite remarkable. To examine more closely the properties of this substance, a number of 1-inch cubes were sawed from the commercial block-carbonate, also some bricks, that is, blocks measuring accurately 2 x 4 x 8 inches, the dimensions of an ordinary brick. The cubes weighed from 2.2 to 2.7 grammes, the bricks weighed 140 to 175 grammes (5 to 6 ounces). The bricks were carefully measured and weighed, and placed in vessels containing distilled water, in which they became gradually submerged, owing to the displacement by water of the air inclosed in the structure of the magnesium carbonate. After twenty-four hours the blocks were removed from the water, dried superficially by contact with filter-paper and weighed. From the increase in weight, the volume of the water absorbed, and consequently that of the air displaced by it, were obtained. For example: a block which when dry weighed 155

Jan 1, 1887

By J. Larsen-Badse

The resistance to dry sliding abrasion us been measured for some hardened and tempered carbon steels. The wear resistance, defined as the reciprocal of the volume loss per unit sliding distance, is found to vary linearly with the hardness of the abraded surface. The data fit two lines, one, of high slope, for the pure metals and for the annealed steels and another, of smaller slope, for the hardened and tempered carbon steels. A relationship is developed showing the alwasion resistance to be proportional to the hardness of the material and to en, where n is the exponent of work hardening. The values of n and of the hardness FOR most materials a high resistance to abrasion is generally associated with a high value of indentation hardness. Brine11 even used the abrasion resistance as a measure of hardness in an attempt at expanding the hardness range covered by his indentation-hardness test.' When comparing different types of materials there is, however, only a very general relation between abrasion resistance and hardness. Sample brittleness seems to contribute to the deviation from a direct relationship. In general, increased brittle- are those relating to the heavily deformed abraded surface. However, for materials having n constant or varying m a regular manner over a wide range of strailts, the wear resistance will also be a linear function of the bulk hardness of the material. For tempered steels containing a dispersion of cementite in ferrite the increase in wear resistance due to the dispersion is found to be a linear function of the volume fraction of Fe3C and of the reciprocal of the mean free ferrite path. This indicates indirectly that the yielding of this material, when it is already heavily deformed, follows the Orowan criterion. ness leads to decreased abrasion resistance.' When comparing materials in the same group, e.g., the metals, the spread is less. Kruschov found that the abrasion resistance of pure metals and of annealed steels is directly proportional to the hardness of the metal. For hardened and tempered steels he obtained another linear relationship, one of smaller slope and intersecting the line for the pure metals at the location of the data for the annealed steels. He also found that the abrasion resistance of cold-worked metals is independent of the degree of cold working. This shows, as he concluded, that the process of abrasion work hardens the metal in the surface region to a very high degree.

Jan 1, 1967

By R. A. Vandermeer, Paul Gordon

On the basis of a unified concept, theoretical erPressions for grain boundary migration in recrys-tallization are derzved for impurity-controlled and impurity-independent migration. The expression in the former case is analogous to that Previously derived by Lucke and Detert, and in the latter is shown to be equivalent to that usually obtained on the basis of absolute reaction rate theory. The equations are tested with quantitative experimental data for boundary migration obtained for the recrystallization of poly crystalline zone-refined alumimnz and for binary "alloys" of this aluminum with 0.00021, 0.00043, 0.0017, 0.0034, 0.0068, 0.0124, and 0.0256 at. pct Cu, respectively. All the essential characteristics of the e@erimentally determined boundary migration rates check both qualitatively ard quantitatively with the predictions of the theoretical equations. THE rates of transformations are customarily analyzed phenomenologically in terms of the two component rates—N, the rate of nucleation and, G, the rate of growth of the nuclei. The scientific aim of both theory and experiment is to describe the fundamental atomic phemmena involved in these two component processes with the hope that parameters calculated from theoretical equations will check those found experimentally. In solid state transformations, the theoretical and experimental problems are both generally of almost prohibitive complexity, for in addition to changes in composition and in such properties as density which may accompany transformations in amorphous, nonrigid materials, transformations in crystalline substances also involve structural changes, crystal reorientations, and the development of stresses. In studying such transformations it thus becomes; highly desirable, if not essential, to focus on a transformation and a set of conditions which minimize the number of active variables. This principle has been applied with considerable success by Cohen and his associates' in their evaluation of nucleation theories using the martensite transformation as the basis of study. A similar possibility exists for the evaluation of growth theories by the use of recrystallization after cold-deforming. If an unalloyed metal is employed as the subject of investigation, the recrystallization transformation involves basically only a change in strain-conditions and orientations. In spite of this possible simplilfication, however, until recently little quantitative success has attended attempts to correlate recrystal1ization parameters measured experimentally with those calculated theoretically. It seems highly probable that this lack of success may be attributed, both in the experimental and theoretical treatments, to one or more of the following factors: a) conditions have usually been studied under which apparently* both nucleation and growth are active;

Jan 1, 1962

By J. Gurland

The wmk is concerned with the estimate of the degee of continuity of a particulate phase dispersed in a matrix. The first section is a verieu: of the parameters nzeasurable by quantitative rnetallogvaphy, namely the contact area and, under certain conditions, the number of contacts between particles of one phase. In the second section, the frequency of particle contacts is related to the degee of continuity of a randomly embedded phase orz the basis of the lattice-percolation model of Hamrnersley and others. THE extent of continuity of the constituent phases may greatly influence the structure-sensitive properties of phase mixtures, particularly if the phase properties differ significantly. An example from the literature1 is shown in Fig. 1. The marked decrease of the electrical resistivity of sintered silver-alumina bodies near 25 pct by volume of silver presumably occurs because the more conductive phase changes from a discontinuous to a continuous structure. Other example of electrical- and thermal-conductivity transitions are cited by kingery In view of these observations, a knowledge and understanding of the connectivity of the microstructure may be of considerable practical importance. This study is concerned with one aspect of the genera1 problem, namely the estimate of the degree of continuity of a particulate phase dispersed in an opaque matrix. The first section reviews the parameters measurable on a polished cross section by auantitative metallography, such as the contact area and under certain conditions, the number of contacts between particles of one phase. In the second section, an attempt is made to relate the frequency of particle contacts to the degree of continuity of a randomly embedded phase. For the purpose of this discussion, the aggregate has two constituents: the particulate phase and the matrix. The latter is considered to be homogeneous. The term "particle" is used with the meaning of "grain", i.e., a minute unit of matter which is usually a single crystal of a readily distinguishable substance within the confines of a simply connected boundary. While many of the concepts which are used here to describe the structural variables characterizing the microstructure of phase mixtures are qualitative and ill-defined, they are presented with the intent of stimulating further work of a more general and rigorous nature. I) PARTICLE CONTACT, CONTIGUITY, AND MEAN FREE PATH 1) Measurement of Contiguity. The fraction of the total internal surface of a phase a shared with particles of that same phase in a two-phase mixture of and $ is indicated by the contiguity ratio:3 whereis the area of the interface between o particles, and Sap is the area of the interface between a particles and matrix P, per unit volume of mixture. The contiguity ratio ranges from 0 to 1 as the distribution of the a phase changes from a completely dispersed to a completely agglomerated structure. The interfacial areas may be obtained from simple intercept measurements on a random plane, after Smith and Guttman where and N are the numbers of intercepts between a random line of unit length on a plane of polish and the interparticle and interphase interfaces, respectively. The equations are valid for any distribution of particle sizes and shapes.

Jan 1, 1967

By H. J. Levinstein, H. J. Guggenheim

RbFeF3 is a transparent ferromagnet with a large faraday rotation which permits the direct observation of magnetic domain structures in bulk crystals. If the position of dislocations within the crystal were known a study of domain wall dislocation interactions would be possible. In this paper an etch pitting solution is described which gives a one-one correspondent between the etch pits and the dislocations intersecting the (100) surfaces of RbFeF3 crystals. In addition, RbFeF3 is shown to have sufficient plasticity so that known arrays of dislocaticms can be put into the crystal. It is concluded that RbFeF, is an ideal material for the investigation of domain wall dislocation interactions. THE influence of lattice defects on the motion of domain walls in ferromagnetic materials has been studied extensively both theoretically and experimentally.4 The experimental data obtained has been qualitative in nature due to the lack either of a quantitative knowledge of the magnetic domain array in the material or of the nature of the dislocation configuration in the material. At room temperature RbFeFJ has the cubic perovskite structure. It is ferromagnetic below 86°K.5,6 It is also transparent and has a large faraday rotation in the magnetic state.7 The domain structure of this material is observable in three dimensions in crystals which are millimeters in thickness.' Since RbFeF3 satisfies the requirements of having an easily visible three-dimensional magnetic domain structure, it was of interest to determine if the dislocation structure of the material could be determined and if the material was sufficiently plastic so that dislocations could be introduced into the as grown crystals. This is a report of the results of that investigation. EXPERIMENTAL PROCEDURE The crystals of RbFeFs used in this experiment were grown by a technique described elsewhere.5 In order to obtain flat strain-free surfaces, the samples were first cut to the crystal orientation desired and the surfaces were polished by employing standard metallographic techniques. The samples were then immersed in a solution of 1 to 3 g of KOH in 100 ml of water. This solution removes the damaged surface layers uniformly leaving a film on the surface of the sample. Etch pits are obtained by immersing the sample in an approximately 50-50 solution of 30 pct peroxide and concentrated acetic acid. The film formed during the KOH treatment turns deep red in color in the etching solution and flakes off the sample. The etching time required depends upon the pit size desired and

Jan 1, 1970

By I. Nilsson, G. Sundkvist, A. Danielsson

A spectrochemical method of slag analysis is descibed which utilizes fusion of the sample with a flux, then cooling and crushing to put all samples into a common form. The powder, is then fed onto adhesive tape and passed through a spark by means of a special device to provide very reproducible discharge conditions. Combined with a direct-reading optical emission instrument, this system provides speed and accuracy of antilysis heretofore unobtainable for. slag samples by any other method. THERE are many suggested methods for spectro-chemical analysis of slags. The most important are fusion-pellet methods and solution methods. In our company the fusion-pellet method has been used earlier, and is described by Lounamaa. W. H. Tingle and C. K. Matocha have made refinements of the pellet method.' A Committee of the British Iron and Steel Research Association has investigated different methods of spectrochemical analysis of slags. Its purpose was to formulate a method which would give the complete analysis in 30 min with an accuracy of ±3 pct. The committee recommends a solution technique, which was thought to correspond best to their requirements. The method to be described is a fusion-tape method. The sample is isoformed by fusion and grinding. The powder is analyzed with the tape technique. The tape machine and some of its applications are described earlier.4'5 The powder to be analyzed is continuously fed onto a moving adhesive tape, which passes through the spark gap. The sparks break through the tape and vaporize and excite the material to be analyzed. The most outstanding feature of the tape machine is its very high reproducibility. The concept of isoformation has been introduced earlier.= It means a pretreatment of the samples to make them uniform from the spectralanalytical point of view, i.e., cancelling systematic differences between the samples. The purpose of the isoformation is to reduce the influence of particle size, as well as chemical and mineral composition. Before describing the isoformation by fusion plus grinding, which is the purpose of this paper, a few words will be said about two other types of isoformations, i.e., grinding with buffer and ion exchange plus grinding as they have been considered during the application of the tape technique for slag analysis. Grinding with buffer might be a sufficient isoformation in some special cases, where the mineral composition is defined. The time of grinding must, however, be rather long, at least 5 to 10 min, even when using such an efficient mill as the Swing Mill from Messrs. Siebtechnik, Mühlheim, Germany. This type of isoformation is not recommended due to its limitations and due to the fact that the gain in time compared with the fusion technique is almost negligible. The principle of ion exchange plus grinding and some of its applications have been described.5 The following elements of interest in slag analysis can be determined in this way: Na, K, Cu, Mg, Ca, Ba, Zn, Pb, Al, Cr, Mn, Fe, Co, Ni. The very important element Si, however, cannot be analyzed with this method. Although the ion exchange isoformation for slag analysis cannot be looked upon as a routine method, it can be used for

Jan 1, 1962

F. G. CLAPP, New York, N. Y. (written discussion *).-Whatever processes of appraisal have been found most correct and feasible in one field or group of fields will generally prove most adaptable in others. So far as the California fields are concerned, Mr. Requa's paper appears to outline the most up-to-date processes of appraisal. It remains, then, to discuss and adapt these and to make such revisions in methods and processes of calculation as will give us results elsewhere. The trouble about most attempts to place a value on oil lands, whether in this country or elsewhere, has been that many of the so-called "experts" called upon to express an opinion either have not possessed the requisite engineering and geological knowledge to make an accurate appraisal of the lands, or that they were not furnished with sufficient information for the purpose in hand. The Independent. 011. Producers' Agency of California, for whom Mr. Requa's original report was prepared, had many advantages in this respect not generally available to engineers making reports, as all existing information seems to have been at the experts' disposal within the limits of a large number of properties, practically commensurate with the extent of the fields in question. Hence the report could be and was more accurate than any similar report for a single company is likely to be in other fields. Very few companies are so exempt from competition that all the data on neighboring leases of other companies will be freely turned over to them. In many companies, certain available data are concealed from the engineer who makes the reports, particularly if the properties are supposed to be worth less than their apparent value. In the case of other companies, having the best of intentions, the data are insufficient to help the engineer greatly in his appraisal, simply because the oil business has been so, unsystematic in most fields that only the largest and wisest companies have kept accurate figures regarding runs and gravity of oil from individual wells and from different depths. In many wells, which ran wild for clays or weeks in the older fields, there was a waste which is not recordable with exactness. These and many other difficulties confront even the most experienced expert in actual practice outside of the California fields. We may justly say, therefore, that an engineer in other fields of the United States and in the European, South American and Asiatic fields, must not only begin where the Independent Oil Producers' Agency

Jan 4, 1918

The mining fraternity of North America was grieved and shocked to learn of the death of Dr. Willet G. Miller on Feb. 10, 1925. Doctor Miller was for many years the Provincial Geologist of Ontario and the one who more than any other had contributed by his personal work and the reports of his subordinates to the recent extraordinary mineral development of the Province. Doctor Miller was fifty-eight at the time of his decease. A man of unusually stalwart physique, he seemed destined to many years of useful service. His friends in both the American and Canadian Mining Institutes can with difficulty reconcile themselves to his loss. Doctor Miller was born in 1867 in Port Rowan, Ont., on the shores of Lake Erie. After preparation in the high school of his native town, he entered the University of Toronto and took his bachelor's degree in 1890. He pursued graduate studies in geology at Chicago, Harvard, and Heidelberg Universities. In 1893, he was first appointed lecturer and soon thereafter Professor of Geology in Queens University, Kingston, Ont., a chair which he held until 1902. He was then appointed Provincial Geologist of Ontario and was placed at the head of the Survey which was attached to the Department of Mines. Within the next year, 1903, he performed the service that made him famous. In the summer of 1903, in connection with the building of the Ontario Government Railway toward an objective on James Bay, veins had been noticed by construction parties just north of what is Cobalt Lake today, and in the rocky pass that is now traversed by the main line of the Canadian National Railway en route to Vancouver. The pink stain of cobalt bloom on the vein, known later as La Rose, caught the eye of a workman; in November, Doctor Miller recognized the silver in it, and brought the possibilities of the district to general attention. In December, he published an article in the Engineering and Mining Journal, stating that the veins could be worked at a handsome profit. During the winter and spring, the mining interest awoke, which resulted in the astonishingly productive silver district of Cobalt; but in which, Doctor Miller, because a government official, scrupulously refrained from having any financial interest whatever. Seldom has so high a sense of honor been manifested; and as the result, Doctor Miller commanded confidence and respect to an extraordinary degree. Hard on the discoveries at Cobalt came, in the next few years, those at the other famous camps in Northern Ontario; and step by step with them, reports issued from

Jan 1, 1925